You're looking for a guide on the "AC4 Tweaker"!
To download the AC4 Tweaker, visit the official Nexus Mods page or the PCGamingWiki. Spend five minutes configuring the sliders. Then, set sail from Havana, climb the crow’s nest, and look out over the blue horizon—now smooth, sharp, and gloriously uncapped. ac4 tweaker
AC4 Tweaker is a utility designed for the PC version of Assassin’s Creed IV: Black Flag You're looking for a guide on the "AC4 Tweaker"
Includes fixes for ultrawide (21:9) resolutions and multi-monitor setups, addressing aspect ratio and UI issues. set sail from Havana